Spring Steel Explained: Grades, Properties, and Uses

Steel springs
Jack Lie CNC machining expert

Specialize in CNC Milling, CNC Turning, 3D Printing, Urethane Casting, and Sheet Metal Fabrication Services.

Spring steel is an essential material for many industries, and it has specific qualities that outperform other types of steel. But what exactly is spring steel and why is it so practical? In this article, we’ll explore what spring steel is, its properties, different grades, how it’s formed, and where it’s commonly used.

Spring steels

What is Spring Steel?

Spring steel is a type of steel that’s specifically used to make springs and elastic components because it can return to its original shape after being bent, compressed, or extended. This ability, known as elasticity in the quenched and tempered state, is due to the high yield strength of steel, which comes from its specific composition and hardening process.

Spring steels are typically made up of medium-to-high carbon content, usually around 0.5 to 1.0 percent. In addition to carbon, they also contain manganese and silicon, with silicon being particularly important in achieving high yield strengths. Products made from these steel alloys can endure continuous bending, compression, extension, or twisting without suffering any permanent deformation.

Manufacturing spring steel requires advanced technical skills to ensure high quality. Any imperfections on the surface, such as decarburization or irregularities, can reduce the fatigue strength. Therefore, it’s essential for manufacturers to ensure that the springs have a perfectly smooth surface for optimal efficiency and performance.

What are the Constituents of Spring Steel?

Spring steels are alloys with a medium-to-high carbon content, usually ranging from 0.5 to 1.0 percent. They also contain other alloy additives such as manganese, nickel, chrome, vanadium, and molybdenum.

However, the essential element in the composition of spring steels is silicon. This material is valued for its durability and ability to maintain its shape and flexibility, making it well-suited for spring steel applications and contributing to the material’s high yield strength. This flexibility allows the material to be deformed and then return to its original position once the load has been removed.

Here are some common spring steel grades and their chemical composition.

Grade C [%] Si [%] Mn [%] P [%] max. S [%] max. Cr [%] max. / – Mo [%] Ni [%] max. V [%]
C55S 0.52 – 0.60 0.15 – 0.35 0.60 – 0.90 0.025 0.010 0.40 0.10 0.40
C60S 0.57 – 0.65 0.15 – 0.35 0.60 – 0.90 0.025 0.010 0.40 0.10 0.40
C67S 0.65 – 0.73 0.15 – 0.35 0.60 – 0.90 0.025 0.010 0.40 0.10 0.40
C75S 0.70 – 0.80 0.15 – 0.35 0.60 – 0.90 0.025 0.010 0.40 0.10 0.40
C100S 0.95 – 1.05 0.15 – 0.35 0.30 – 0.60 0.025 0.010 0.40 0.10 0.40
51CrV4 0.47 – 0.55 0.40 0.70 – 1.10 0.025 0.010 0.90 – 1.20 0.10 0.40 0.10 – 0.25
80CrV2 0.75 – 0.85 0.15 – 0.35 0.30 – 0.50 0.025 0.010 0.40 – 0.60 0.10 0.40 0.15 – 0.25
Spring steel for cylinder block

Classification of Spring Steel

As per the steel classification standard GB/T 13304, spring steel is categorized as steel for mechanical structures based on its fundamental performance and service characteristics. In terms of quality grade, it falls under the special quality steel category, requiring strict control over its quality and performance during production. In Chinese custom, spring steel is considered special steel.

Based on the chemical composition, spring steel is further classified into carbon spring steels, alloy spring steels, stainless spring steels, copper-based spring alloys, and nickel-based spring alloys.

Here is the classification of spring steels based on their chemical compositions.

Stainless Steel 1Cr18Ni9 SUS302 302 1.4310
0Cr18Ni9 SUS304 304 X5CrNi18-10
0Cr17Ni12Mo2 SUS316 316 X5CrNi17.12.2
07Cr17Ni7A1 SUS631 SAE17-7 X7CrNiAL17.7
Nickel-based GH4169 GH169 InconelX-718 NiCrl9Fe19Nb5、Mo3
GH145/GH4145 NCF750 Incone1X-750 NiCr15Fe7TiAl
Alloy-based 60Si2MnA SUP6 SAE9260 60Si7
50CrVA SUS10A 6150 67SiCr5
60Si2CrA SUP12 SAE9254 67SiCr5
Carbon-based 65Mn 1066 Ck67
Music Wire SWP-B/ SWP-A
Copper-based QSn4-3(Tin Bronze) C3712 C28000 CuZn40
QSi3-1(Silicon Bronze) C6561
QBe2(Beryllium Bronze) C1720 C17200
Monel 400 NW4400 UNS N04400 2. 4360
Monel K500 NW5500 UNS N05500 2. 4375


Chemical Composition

65MnGB/T 1222-20070.62~0.700.17~0.370.90~1.20≤0.035≤0.035≤0.25≤0.25≤0.25

Mechanical Properties

Tensile Strength Rb(MPa)Yield Strength Rs (MPa)Shear Modulus G/x103(MPa)Elastic Modulus E/x103(MPa)Recommended Temp

Characteristics & Application

65Mn is a kind of high-carbon steel. It has simple composition and low cost. Manganese is added to improve hardenability. Its comprehensive mechanical properties, decarburization, and other properties are better than carbon steel. But 65Mn is sensitive to elevated treatment and cracking easily when quenching.

65Mn is commonly used to manufacture a variety of round springs, clockwork, spring rings, vibration dampers, and clutch springs.

Music Wire

Chemical Composition


Mechanical Properties

Tensile Strength Rb(MPa)Yield Strength Rs (MPa)Shear Modulus G/x103(MPa)Elastic Modulus E/x103(MPa)Recommended Temp

Characteristics & Application

Music wire is cold drawn after quenching in a lead bath. It is a high spring with very high strength, elasticity, and fatigue resistance. It is a widely used small spring material and is used to manufacture various important springs, various high-stress mechanical springs, and valve springs.


Chemical Composition

60Si2MnGB/T 1222-20070.54~0.601.5~2.00.70~1.00≤0.035≤0.035≤0.35≤0.35≤0.25

Mechanical Properties

Tensile Strength Rb(MPa)Yield Strength Rs (MPa)Shear Modulus G/x103(MPa)Elastic Modulus E/x103(MPa)Recommended Temp

Characteristics & Application

The manganese in 60Si2Mn can improve the hardenability. Due to its high silicon content, its strength, hardenability, and tempering resistance are higher than those of carbon spring steel. However, due to its high silicon content, it has a high likelihood of surface decarburization and low cold deformation plasticity. After quenching and tempering, it has a higher yield-strength ratio, anti-relaxation ability, and tempering stability, especially the fatigue life is significantly improved.

60Si2Mn is suitable for manufacturing coil springs with a thickness of cross-section less than 25mm, and is widely used in heavy machinery, railway vehicles, and automobiles.


Chemical Composition

55CrSiGB/T 1222-20070.50~0.601.2~1.60.50~0.800.50~0.80≤0.030≤0.030≤0.20≤0.20

Mechanical Properties

Tensile Strength Rb(MPa)Yield Strength Rs (MPa)Shear Modulus G/x103(MPa)Elastic Modulus E/x103(MPa)Recommended Temp
1862 (φ≥4.2mm)166678.8196.0-40~250

Characteristics & Application

55CrSi spring steel has high fatigue resistance and high relaxation resistance. Because the mass fraction of Si in it is relatively high, the elastic limit, yield-to-strength ratio, and resistance to fatigue can be significantly improved. Cr element is also added to enhance the mechanical properties. Cr has low sensitivity to elevated treatment, helping to eliminate the graphitization tendency of Si-containing spring steel.

55CrSi is widely used in the manufacture of brake springs, solid stabilizer bars, torsion bars, valve springs, shock absorber springs for high-end motorcycles, and mechanical springs for important purposes.


Chemical Composition

50CrVAGB/T 1222-20070.46~0.540.17~0.370.50~0.800.80~1.100.10~0.20≤0.03≤0.03≤0.35≤0.25

Mechanical Properties

Tensile Strength Rb(MPa)Yield Strength Rs (MPa)Shear Modulus G/x103(MPa)Elastic Modulus E/x103(MPa)Recommended Temp
1274 (φ=10mm)112778.8196.0-40~250

Characteristics & Application

50CrVA has good mechanical properties and high hardenability. The vanadium is integrated to refine the grains of steel, thus improving strength, toughness, and heat resistance. However, its weldability is poor. 50CrVA is a high-grade spring steel, used for large-section and high-load applications such as valve springs, piston springs, and safety valve springs.


Chemical Composition

30W4Cr2VAGB/T 1222-20070.26~0.340.17~0.37≤0.042.00~2.500.50~0.804~4.5≤0.03≤0.03≤0.35≤0.25

Mechanical Properties

Tensile Strength Rb(MPa)Yield Strength Rs (MPa)Shear Modulus G/x103(MPa)Elastic Modulus E/x103(MPa)Recommended Temp
1470 (φ=10mm)132381.8~78.7206.0~196.2-40~500

Characteristics & Application

30W4Cr2VA contains tungsten, chromium, and vanadium. The main function of tungsten (w) is to improve the quenching ability and heat resistance of steel, so that the spring maintains high strength and elasticity at high temperatures. Tungsten can also improve tempering stability and hot workability. It is used in the quenched and tempered state and used as heat-resistant springs, such as main safety valve springs in boilers, etc.


Chemical Composition

60Si2CrAGB/T 1222-20070.56~0.641.40~1.800.04~0.700.70~1.00≤0.030≤0.030≤0.35≤0.25

Mechanical Properties

Tensile Strength Rb(MPa)Yield Strength Rs (MPa)Shear Modulus G/x103(MPa)Elastic Modulus E/x103(MPa)Recommended Temp
1764 (φ=10mm)156881.8~78.7206.0~196.2-40~250

Characteristics & Application

60Si2CrA is a high-strength spring steel. It has high hardenability and good heat treatment performance. Because of its high strength, the internal stress should be eliminated in time after rolling. 60Si2CrA can be used to manufacture steam turbine seal springs, adjustment springs, condenser support springs, high-pressure water pump disc springs, etc. It can also be used to make conventional weapon retrieval hook springs, crusher springs, and engineering machinery springs.

Stainless Spring Steel

Chemical Composition

SUS302JIS G4314≤0.15≤1.00≤2.00≤0.0308.00-10.0017.00-19.00≤0.045 
SUS304JIS G4314≤0.15≤1.00≤2.00≤0.0308.00-10.0017.00-19.00≤0.045 
SUS316JIS G4314≤0.15≤1.00≤2.00≤0.03010.00-14.0016.00-18.00≤0.0452.0~3.0
SUS631JIS G4314≤0.09≤1.00≤1.00≤0.036.5-7.7516.0-18.0≤0.04Al 0.75~1.5

Mechanical Properties

GradeTensile Strength Rb(MPa)Tensile Strength Rs (MPa)Shear Modulus G/x103(MPa)Elastic Modulus E/x103(MPa)Recommended Temp
SUS302/3041863~2108 (φ=1mm)≥20571.7193.2-200~200
SUS3161863~2108 (φ=1mm)≥20571.7193.2-200~200
SUS6311705~2010 (φ=1mm)≥20571.7193.2-200~343

Characteristics & Application

As a widely used spring steel, it has good resistance to low temperature, corrosion, and heat.

  • SUS302/304: Corrosion-, heat-resistant spring steel. Their mechanical properties are the same, but 304 is more corrosion-resistant than 302.
  • SUS316: Due to the addition of Mo, its resistance to corrosion and high temperature is particularly good. It is usually used in navigation and resistance to chloride corrosion.
  • SUS631: Higher strength than 300 series stainless steel. It has high strength, high hardness, and resistance to fatigue, heat, and corrosion. Used in aerospace, chemical, petrochemical, paper and metal processing industries.

Inconel 750

Chemical Composition

Inconel X750AMS 5698≤0.0814.0~17.0≥70.00.40~1.002.25~2.755.00~9.000.70~1.20≤0.501.0≤0.01≤0.5

Mechanical Properties

Tensile Strength Rb(MPa)Yield Strength Rs (MPa)Shear Modulus G/x103(MPa)Elastic Modulus E/x103(MPa)Recommended Temp

Characteristics & Application

It’s a nickel-based alloy reinforced with Al, Ti, and Nb. Aluminum (A1), titanium (Ti), and niobium (Nb) are mainly added to stainless steel for springs or other spring materials for special purposes. The main purpose is to improve the corrosion resistance of the material. Ti is a strong deoxidizer in steel, which can refine grains and reduce sensitivity. Nb can refine grains and reduce overheating sensitivity, and brittleness of steel. It is one of the better alloys in the early Inconel alloy system. It has good strength, corrosion resistance, and oxidation resistance under 980℃.

Inconel X-750 alloy is mainly used to manufacture relaxation-resistant flat springs and coil springs that require higher strength.

Inconel 718

Chemical Composition

Inconel 718AMS 5662≤0.0817.0~21.050.0~55.0≤1.00.20~0.800.65balance2.8~3.3≤0.35≤0.35≤0.3

Mechanical Properties

Tensile Strength Rb(MPa)Yield Strength Rs (MPa)Shear Modulus G/x103(MPa)Elastic Modulus E/x103(MPa)Recommended Temp

Characteristics & Application

Inconel 718 is a Fe-Ni-Cr alloy. It has excellent resistance to high temperatures and corrosion. It has high strength and good toughness below 650°C, as well as oxidation and corrosion resistance in high and low temperature environments. It can be widely used in various high-demand situations, such as steam turbines, fuel rocket cryogenic engineering, acidic environments, nuclear engineering, etc.


Chemical Composition

ElgiloyAMS 5833≤0.1539.0~41.0≤0.119.0~21.0balance6.0~8.01.5~2.5≤1.214.0~16.0≤0.015≤0.015

Mechanical Properties

Tensile Strength Rb(MPa)Yield Strength Rs (MPa)Shear Modulus G/x103(MPa)Elastic Modulus E/x103(MPa)Recommended Temp
1515-2000 77.2190-184~454

Characteristics & Application

Elgiloy is a cobalt-chromium-nickel alloy. The addition of cobalt allows the material to reach a high elastic limit, and the alloy also has excellent corrosion resistance and fatigue resistance in many environments. It is suitable for applications where high corrosion resistance is required or low relaxation at temperatures up to 380°C is required. In seawater, Elgiloy alloy is almost immune to crevice corrosion and stress corrosion. It’s widely used for oil and gas extraction, medical, dental, aerospace, defense, space exploration and watchmaking.

Copper-based Spring Steel

Chemical Composition

GradeStandardCuSnZnAlSiNiFeBeTotal Impurities
Tin BronzeGB/T 13808balance3.5~4.52.7~3.30.0020.002 0.05 ≤1.5
Silicon BronzeGB/T 4423balance0.250.50.03(Pb)2.75~≤1.1
Beryllium BronzeGB/T 5231balance 0.150.05(Pb)≤0.5

Mechanical Properties

GradeTensile Strength Rb(MPa)Yield Strength Rs (MPa)Shear Modulus G/x103(MPa)Elastic Modulus E/x103(MPa)Recommended Temp
Tin Bronze780~1130 4020793163-250~120
Silicon Bronze780~1130 4020793163-40~120
Beryllium Bronze373~1275 42169129448-200~120

Characteristics & Application

Tin bronze has good corrosion resistance in the atmosphere where a dense tin dioxide film is formed on the surface of tin bronze. The denser and thicker the tin dioxide film, the better the wear resistance. It is also corrosion-resistant in fresh water and seawater, and is suitable for manufacturing springs that require higher hardness and stronger wear resistance.

Silicon bronze contains manganese and nickel elements. It has high strength and strong corrosion resistance. It has high corrosion resistance in fresh water and seawater, and has good weldability and cutting properties. It’s used to manufacture friction parts (such as guide sleeves for engine exhaust and intake valves) and structural parts working in corrosive media.

Beryllium bronze contains 1.7~2.5% beryllium. The addition of beryllium makes it have excellent elasticity. It is a precipitation hardening alloy with good strength, hardness, elasticity, and fatigue resistance. It has a service life of more than 40 years in seawater. It is widely used and expensive, and is more suitable for manufacturing precision springs on electrical appliances.


Chemical Composition

Monel 400AMS 723363.0~70.028.0~34.0  ≤2.0≤0.5≤0.3≤2.5≤0.024
Monel K500QQ-N-28663.0~70.0balance0.35~0.852.3~3.15≤1.5≤0.5≤0.25≤2.0≤0.001

Mechanical Properties

GradeTensile Strength Rb(MPa)Yield Strength Rs (MPa)Shear Modulus G/x103(MPa)Elastic Modulus E/x103(MPa)Recommended Temp
Monel 4001000~1240 65.5179-184~260
Monel K5001100~1380 65.5179-184~232

Characteristics & Application

Monel 400 is a nickel-copper alloy. This alloy has excellent corrosion resistance in hydrofluoric acid and fluorine gas media, and also has excellent corrosion resistance against hot concentrated alkali liquid. It is also resistant to corrosion from neutral solutions, water, seawater, atmosphere, organic compounds, etc.

Monel K500 is a precipitation hardened nickel-copper-aluminum alloy. The addition of titanium and aluminum elements increases the tensile strength of K500 to twice that of 400 alloys, and the yield strength is three times that of 400 alloys. The material remains ductile and tough at temperatures as low as -240°. K500 also offers spark resistance and excellent corrosion resistance to a wide range of chemical elements and maritime environments, such as salts, alkalis, acids, and non-oxidizing acids.

Properties of Spring Steel

Spring steel is widely used in the manufacturing of various types of springs and similar components. It is distinguished by its high yield strength, allowing products made from this material to endure continuous compression, bending, and twisting without losing their original shape.

Here are some key characteristics of spring steel:

  • Resilience: Spring steel is highly resilient and can return to its original shape after being bent or stretched.
  • Hardness and durability: It can bear heavy loads without breaking and is resistant to weathering and wear over time.
  • Elasticity: Spring steel can be shaped, formed, and post-heat treated without losing its form.
  • Corrosion resistance: It has high corrosion resistance, making it suitable for use in harsh conditions.

In addition to high yield strength, spring steels also possess excellent tensile strength and fatigue strength. These properties make spring steel suitable for a wide range of industrial applications.

The table below summarizes the yield and tensile strengths of different spring steel grades – EN 10132-2021.

Material No. Standard Annealed to spheroidized cementite Annealed to spheroidized cementite-dead soft
AISI JIS EN DIN Yield strength[MPa](max.) Tensile strength[MPa](max.) HBW(max.) Yield strength[MPa](max.) Tensile strength[MPa](max.) HBW(max.)
Metric US Metric US Metric/US Metric US Metric US Metric/US
1.1231 1070 SK7 C67S Ck 67 380 55 580 84 180 330 48 550 80 171
1.1248 1075 SK6 C75S Ck 75 400 58 610 88 189 345 50 570 83 177
1.1284     C80S   400 58 610 88 189 345 50 570 83 177
1.1269 1086 SK5 C85S Ck 85 405 59 620 90 192 355 51 580 84 180
1.1217     C90S   420 61 630 91 195 365 53 590 86 183
1.1274 1095 SK4 SK3 C100S Ck 101 430 62 640 93 198 380 55 600 87 186
1.1224     C125S   440 64 650 94 202 400 58 620 90 192
1.2002   SK2 125Cr2 125Cr1 450 65 660 96 205 385 56 640 93 198
1.2235     80CrV2 80CrV 2 390 57 600 87 186 345 50 570 83 177
1.5026 9255   56Si7   420 61 620 90 192 360 52 580 84 180
1.5634   SKS51 75Ni8   450 65 660 96 205 400 58 630 91 195
1.8159 6150 SUP10 51CrV4 50 CrV 4 380 55 580 84 180 330 48 550 80 171
1.8161     58CrV4 58 CrV 4 390 57 590 86 183 350 51 560 81 174
1.2003     75Cr1   420 61 630 91 195 360 52 580 84 180
1.2018     95Cr1   430 62 640 93 198 380 55 600 87 186
1.6595     68CrNiMo3-3   400 58 615 89 190 350 51 575 83 179

How is Spring Steel Formed?

Spring steel

Spring steel can undergo various processes, such as hot and cold rolling, annealing, and heat treatment, depending on the grade of spring steel and the desired mechanical properties of the final product.

The process typically begins with melting and refining the raw materials to achieve the correct steel composition. The molten steel is then poured into large blocks or billets and allowed to cool. The billets can be additionally processed through either hot or cold rolling to decrease their thickness and improve their grain structure, effectively increasing the material’s tensile strength and producing spring steel sheets, strips, rods, and bars. Higher reductions lead to increased tensile strengths, but excessive tensile strength may cause the material to become brittle and susceptible to breakage. Cold rolling is commonly favored for high-quality spring steel due to its ability to provide finer control over the thickness and dimensional tolerances.

Upon rolling, the steel may be annealed to relieve internal stresses and enhance its ductility. This involves heating the steel to a specific temperature for a set duration and then allowing it to cool slowly in a controlled environment, thereby enhancing the toughness and flexibility of the steel.

Lastly, spring steel can undergo heat treatment to attain the desired mechanical properties. A specific percentage of carbon is essential to enable this process, typically ranging from 0.50% to 1.25% for carbon spring steels. This process includes heating the steel to a critical temperature and then quickly cooling it (quenching) to form a hard, brittle structure. Subsequently, the steel may be tempered through a reheating process, which alleviates stresses and enhances its toughness. Heat-treated spring steel is used for making products such as flat springs, saw blades, and knives.

Common Uses & Applications of Spring Steel

Because of its exceptional characteristics, spring steel is often referred to as general-use steel. It is primarily utilized in the production of high-quality saw blades, lock picks, antennas, and scrapers, particularly when in a hardened and tempered state for making flat springs that are challenging to shape.

As a versatile type of steel, spring steel has a wide range of applications. It’s commonly used for creating:

  • Clips & fasteners: Its high strength and resistance to fatigue make spring steel ideal for producing clips and fasteners.
  • Springs: Used in various machinery and vehicular parts, spring steel is commonly employed for coil springs, compression springs, torsion springs, and leaf springs.
  • Medical equipment: Spring steel is used in the creation of medical instruments such as surgical tools and orthodontic appliances.
  • Machinery: It is used for manufacturing machinery and equipment, including lawnmowers, aircraft, conveyors, and pumps.
  • Hand tools: Its high strength makes spring steel perfect for crafting strong, durable tools like pliers, wrenches, and scissors.
  • Piano wire: Also known as music wire, spring steel is used in a variety of applications including spring clamps, antennas, and vehicle coil springs or leaf springs.
  • Lockpicks: Spring steel’s pliability and resilience make it a popular material for fabricating lockpicks.
  • Landing gear: Tubular spring steel is utilized in the landing gear of some small aircraft due to its ability to absorb landing impact.
  • Shims: It is extensively used in shims and binder clips for its resistance to deformation in low thicknesses.
Motorcycle shock absorber spring


Steel is a combination of iron and carbon, with additional elements incorporated to improve its characteristics. Various steel types exist, each possessing distinct properties based on their unique composition and manufacturing methods.

Spring steel is a specific type of steel designed for its exceptional yield strength, elasticity, hardness, and resilience, making it well-suited for applications like springs, as well as retaining clips and tabs.

The superiority between the two really relies on the specific application. When it comes to components like springs, automotive suspension parts, and other mechanical components facing cyclical stresses, spring steel is the better choice.

Nonetheless, for applications not requiring substantial elasticity, resilience, and tensile strength, regular or other forms of steel will be more economical and suitable. Using spring steel also has its drawbacks, such as requiring extra considerations for machining and welding.

Spring steel shall have outstanding overall properties, including mechanical properties (especially strength limit, elastic limit, and yield ratio), resistance to elastic relaxation (also known as anti-relaxation performance), fatigue performance, hardenability, as well as physical and chemical properties (such as oxidation, heat, low temperature, and corrosion resistance).

To fulfill the aforementioned performance requirements, spring steel requires excellent metallurgical quality (high purity and uniformity), superior surface quality (enforced control of surface imperfections and decarburization), and precise shape and size.

The strength of spring steel is determined by its properties and the particular application it serves. In general, spring steels with higher carbon content tend to be stronger and offer better fatigue resistance compared to those with lower carbon content.

One of the most robust and commonly utilized spring steels is AISI 1095, characterized by a carbon content of approximately 0.95%, providing exceptional strength and resilience. It is frequently employed in the manufacturing of high-stress springs and components requiring superior strength and endurance.

Another highly robust spring steel variant is AISI 6150, also referred to as chrome vanadium steel. This alloy steel includes chromium and vanadium along with carbon, bestowing it with a blend of high strength, toughness, and fatigue resistance. AISI 6150 is commonly utilized in the production of springs and components necessitating elevated strength, such as truck springs and other heavy-duty applications.

Other strong spring steel grades are like AISI 5160, incorporating manganese and silicon alongside carbon, and AISI 4340, a nickel-chromium-molybdenum alloy steel recognized for its exceptional strength and toughness.

Determining the strongest type of spring steel relies on the particular demands of the application, covering factors such as stress levels, cycle frequency, and the operating environment of the component.

Generally, spring steels are designed to possess high hardness and strength, enabling them to endure the strains of repeated loading and unloading without distorting or fracturing. The hardness of spring steel is commonly assessed using the Rockwell hardness scale, which gauges the depth of penetration of a diamond or tungsten carbide indent into the material.

Spring steel typically exhibits a Rockwell hardness (HRC) range of 44-57, varying based on the specific grade and heat treatment applied. For instance, AISI 1095 spring steel usually attains a Rockwell hardness of approximately 55-57 following quenching and tempering, while AISI 5160 spring steel typically achieves a Rockwell hardness of about 52-56 after heat treatment.

Indeed, spring steel can be machined, while it is generally more challenging to machine compared to low-carbon steel owing to its hardness. Machining spring steel usually necessitates the utilization of a hard, sharp cutting tool and low cutting speeds to prevent excessive heat accumulation that could potentially harm the tool and/or the workpiece. Additionally, workpieces crafted from spring steel may be susceptible to hardening during machining, thereby posing increased difficulty as the process unfolds.

To enhance the machinability of spring steel, it can be annealed or pre-hardened prior to machining. Annealing involves heating the spring steel to a specific temperature and slowly cooling it to soften the material. This can facilitate easier machining, but it may also diminish the material’s springiness and strength. On the other hand, pre-hardened spring steel has already undergone a heat treatment process to attain a particular hardness, making it easier to machine while still retaining some of its desirable properties.


Today, spring steel plays a vital role in the production of various items and is expected to maintain its significance across several industrial fields. For instance, it is commonly used in applications that demand components capable of consistently absorbing and reapplying force, such as the spring diaphragms in automobiles and the retractor springs in seat belt systems. The elasticity of spring steel holds a crucial function in the operation of these dynamically stressed parts, determining the amount of force the material can withstand without suffering permanent deformation.

Spring Steel CNC Machining at Runsom Precision

Steel spring

CNC machining spring steel is a relatively complex process, and the selection and use of tools have a very important impact on the quality and efficiency of the process. If you have needs in spring steel machining, reach out to Runsom Precision; we support the machining of a wide range of spring steel materials as well as work hardening and heat treating services. Our experts are well-versed in the technical standards and properties of spring steels to provide the optimal solution for your project. Get an online quote today!

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